Robert Max Wilke was born Reinhard Maximilian Wilke in Insterburg, East Prussia (now Chernyakhovsk, Russia) on July 30, 1862, the son of Eveline Cruse and M. C. H. Wilke. He visited America in 1884 and 1888, perhaps examining the possibilities for someday making a new life in the U.S., and married Anna Koehne in Gotha Florida in 1888 (she died in 1889, after giving birth to their son, Karl Friedrich Wilke).

Wilke and his second wife, Elisabeth Osthoff (who had been born in Oldenburg) were married in Germany in 1890. After their marriage, they came to the U.S. together in February 1891, with their infant son Karl. They settled in Gotha, Florida, a German pioneer community near present-day Orlando, where their daughters Elisabeth and Marie were born in 1891 and 1895 respectively, and their son George was born in 1892. Wilke tried to make a living there growing oranges, but gave up after a bad frost killed his trees in 1896. They then returned to Europe and lived in Trieste, Austria for a few years, where Wilke worked as a marine insurance adjuster for the Austrian Lloyd Company, and where their daughter Charlotte and son Reinhard were born in 1897 and 1902 respectively. They finally returned to the U.S. permanently in 1904, leaving behind his 15-year-old son Karl and settling first in Orange County, California (where their son George was killed in an accident), then Lodi, then Berkeley, then finally near Mayfield (now Palo Alto) in Santa Clara County, where Wilke once again took up fruit farming.

Wilke was an ardent gem and mineral collector; he took every opportunity to visit the working pegmatite mines in southern California to collect specimens. He began advertising "beautiful California minerals" (including tourmaline, beryl, kunzite and others) for sale in The Mineral Collector in 1906, giving his address as 2627 Piedmont Avenue, Berkeley, California. He was there when the great earthquake of 1906 struck San Francisco, and was among those who went across the bay to give aid. In March 1907 his ad offered "very fine Tourmalines of various colors, Kunzites, Beryls, Topazes, Gold Quartz, elegant crystallized Native Copper from Arizona," giving his address as Box 312, Palo Alto, California.

In October 1907 Wilke made a deal with Roderick Dallas, owner of the Dallas Gem benitoite mine in San Benito County, to take all of the neptunites and the benitoites that had insufficient gemstone potential and sell them as specimens to collectors, splitting the receipts 50-50. Wilke thus became the main route by which good specimens were saved and sold to collectors instead of being chopped up to yield gem rough. He took 50 pounds of specimens home with him on that first visit to the mine. In November 1907 he began advertising fine specimens of benitoite and neptunite for sale. Over the next four years, hundreds of pounds of benitoite and neptunite specimens were shipped to Wilke for processing and sale, many of them collected in the mine by Wilke himself.

In 1909 Wilke visited the famous Tourmaline King mine in San Diego County and purchased some of the largest and finest matrix tourmaline specimens ever found there. Some of these he kept for his personal collection and some he sold to major museums. On the 1910 census he is listed as a "farmer and mineral collector for universities."

During the summer of 1913, Wilke took mineralogist Arthur S. Eakle from the University of California, Berkeley, on a collecting trip to the Crestmore quarry in Riverside County, where they collected a large suite of specimens. Included in what they found was an unknown which Eakle and Stanford mineralogist Austin F. Rogers (1914) subsequently described as the new mineral wilkeite—“in honor of R. M. Wilke, who as a mineral collector and dealer has done much to advance the science of mineralogy.” The species definition stood for 68 years, but in 1982 it was discredited as a phosphate-rich variety of fluorellestadite.

Wilke kept in contact with many of the mineralogists of his day and was always ready to contribute specimens for research. He provided cristobalite and lapis lazuli to Austin F. Rogers at Stanford University; nontronite to O. P. Mehra and M. L. Jackson at the University of Wisconsin; wilkeite to Duncan McConnell at the University of Minnesota; kleinite to William F. Hillebrand and Waldemar T. Schaller; zunyite to Linus Pauling; and strigovite, copiapite, rosenbuschite, thorite to Esper S. Larsen. He donated the type specimen of joaquinite (which he had obtained from George Louderback) to the Harvard Mineralogical Museum. And he provided much information from his personal knowledge to J. Murdoch and R. W. Webb for use in the preparation of Minerals of California (1948).

The Tourmaline King mine continued to hold Wilke's fascination, and he believed there was potential for more discoveries there. Around 1916 he purchased the patented mine and for the next six years or so he carried out a very thorough exploration for more tourmaline. Considerable amounts of lepidolite, morganite, tourmaline and kunzite were said to have been produced before work ceased. (Wilke's heirs finally sold the mine in 2002.) Wilke became well-known and respected as a reputable mineral dealer, and continued to advertise periodically in Rocks & Minerals as late as 1932.

Sometime in the 1930s or early 1940s Wilke closed out his business and sold off his remaining stock of minerals. After he injured his shoulder in a fall from a tree in 1935, he and Elizabeth traveled to Germany in order for him to spend time recuperating at a spa. Furthermore, Elizabeth had inherited some money, which under Nazi law could not be taken out of the country, so they figured they might as well enjoy spending it in Germany.

Western Mineral Exchange of Seattle announced in August 1944: "We have purchased...the last eleven hundred pounds of the stock of Mr. R. M. Wilke, of Palo Alto, and his collection of duplicates. Mr. Wilke was famed for the excellence of his material and the preciseness and accuracy of his identification." Robert M. Wilke died of cancer on September 16, 1946. Wilkie Way in Palo Alto, which passes near his old apricot orchard, was named for him.